L-39 Albatros: Own and Fly a Fighter Jet

L-39 Albatros: Own and Fly a Fighter Jet

L-39 Albatros: Own and Fly a Fighter Jet

 The dream of flight began when we became enviously aware of our avian cohabitants. Pilots who have achieved this dream are summoned by a siren song offered in various meters. Some are drawn to a remote terminus difficult to reach by commercial carriage (traveling without interaction with TSA is a major benefit). Many merely love to fly, enjoying the journey as much, if not more, than the destination. I count myself among this latter group, a subset of which includes adrenaline seekers and aficionados with aerobatic intentions. My rabid ilk chases speed and acceleration and enjoys the challenge of the perfect whifferdill.  

There is a suitable aircraft for every mission. Travelers need speed, reliability and luggage space. Those hungry for the next hundred-dollar hamburger just need wings. For aerobatics, it is a purpose-built craft that can sustain increased flight loads. For the last 43 years, I have been privileged to experience aviation as a pilot, airplane builder, aircraft mechanic, Flight Instructor and FAA examiner. From this perspective, I am confident in saying that if you want to not only fly fast but also upside down, a most excellent option is the Aero Vodochody L-39 Albatros. 

Front and rear cockpit of Greenwald’s L-39. For a pilot with jet experience, an L-39 type rating can be accomplished with no more than a few hours of transition training. For those new to jets, plan on 10-15 hours depending on aptitude and prior experience.

Background

The L-39C Albatros is a high-performance jet trainer designed in Czechoslovakia in the 1960s – one of the very first to be equipped with a turbofan powerplant. More than 2,800 were built, some of which were deployed for combat in the –ZO configuration with heavier wheels and brakes and extra hardpoints under the wings. 

Ruggedly designed for operations from unimproved fields, the L-39 has proven to be a reliable machine well-suited for a civilian role as an aerobatic PLJ (personal light jet). Currently, 234 L-39 jets are registered in the United States, making the Albatros one of America’s most popular jet warbirds.  

The L-39 has serious ramp appeal. With its sharply tapered nose, narrow fuselage, and twin over-the-wing air intakes, it looks like it is built to go fast. The top of the tail is more than 15 feet above the ground, and the almost 40-foot length is balanced by 31-foot wings mounted to the aft fuselage. Wingtip fuel tanks and duel needle-like pitot-static masts complete its distinctive appearance. Large bubble canopies enclose front and rear cockpits. The aft seat is elevated, so both pilots enjoy tremendous visibility. The cockpits are roomy, and with adjustable rudder pedals and electric seat elevation controls, pilots of all sizes can be comfortably accommodated. For aircraft equipped with hot ejection seats, there is an adjustment for pilot weight. 

The L-39 is sturdy and simple to operate. High over-the-wing air intakes minimize the risk of FOD (foreign object damage) when operating on and off unimproved strips. Landing gear, flaps and spoilers are hydraulically activated by an engine-driven pump that supplies constant pressure to main and emergency circuits. If the pump fails and main system pressure is depleted, there is a pilot-operated interconnect that allows gear, flaps and brakes to be activated from the emergency circuit. Dual accumulators store additional hydraulic energy and serve as dampeners for pressure fluctuation during operation.

Electricity is supplied by a large generator backed up by a ram air turbine generator (RAT) that automatically deploys from the aft lower fuselage in case of generator failure. In many aircraft, this heavy system is removed and electrical back-up is provided by a battery bank in the nose with up to 5,200 amp-hours of reserve. The battery bank helps maintain weight and balance since the aircraft tends to be tail-heavy when armaments are removed. Maximum amperage for all systems never exceeds 50 amps in flight, so the large batteries provide more than enough emergency power.

One of the more interesting systems is the Saphir 5 starter unit. This is a stand-alone jet engine that supplies air power to start the AI-25TL engine. The Ivchenko powerplant is a low bypass (1.7:1) turbofan that supplies 3,800 pounds of thrust. The engine is protected by an RT-12 EGT Limiter that interrupts fuel flow in an over-temperature situation. An override switch deactivates the RT-12 for emergency fuel delivery. Fuel is carried in the fuselage (290 gallons) with standard wing tip tanks holding an additional 54 gallons. The five interconnected fuselage fuel tanks require patience when fueling; the last 5-7 gallons are added slowly as the tanks will slowly “burp” trapped air when almost full. A 3-gallon dedicated “negative G” fuel reservoir allows no more than 20 seconds of inverted flight. Auxiliary fuel tanks can be fitted under the wings and in the fuselage. Fuel management is automatic, with bleed air pressure driving fuel from the tip tanks to the main fuselage tank. An electric low-pressure pump takes over from there to feed the engine’s high-pressure injector. Bleed air is also used to pressurize the cockpits. This is done automatically to a max pressure differential of 3.5 PSI for a 12,500-foot cabin at 21,000 ft. Above this altitude supplemental oxygen is provided via an onboard system.

Most converted civilian aircraft have an empty weight of about 7,000 pounds. The Max Gross Weight of 11,485 (11,830 for –ZO) allows a full-fuel payload of more than 1,500 pounds – plenty for two pilots and their bags.

The performance is impressive: Mmo is 0.8 Mach with typical high-speed cruise speeds of 340 KTAS at FL180. The plane I fly does a bit better than that at 370 KTAS, probably due to its light weight. Fuel burn in the L-39 is also impressive, but like all turbine-powered aircraft, this rapidly decreases with altitude. On take-off, the engine rips through almost 400 gallons per hour (gph). High-speed cruise at FL180 draws about 180 gph. Closer to the service ceiling of 37,000 feet, TAS is 300 kts, and fuel burn drops to 120 gph. 

Because it is a turbofan-powered aircraft, piloting the L-39 requires a type rating. For a pilot with jet experience, this can be accomplished with no more than a few hours of transition training. For those new to jets, plan on 10-15 hours depending on aptitude and prior experience. Pilots must have 1,000 hours TT with 500 hours PIC. Ground school is a must. The Albatros is certified in the Experimental/Exhibition category so renting one for training is disallowed by the FAA unless the aircraft provider has a Letter of Deviation Authority (LODA). 

Preflight 

The preflight starts in front of the left wing. A look down the yawning air scoop allows inspection of the fan blades. On the left fuselage, an access panel is opened to check the nitrogen charge of the twin hydraulic accumulators. Higher up, another access panel opens to check the hydraulic fluid reservoir (for an accurate reading the system must first be depressurized). After a look up the tailpipe, engine oil is checked through a clear window on the right fuselage. Tires and brakes are checked, as are the wheel wells. A panel on the left nose cone provides access for two toggle switches that energize the fire detection/suppression system and the ejection seat circuits. Pencil-like barber poles stick up through the nose and the wing roots to provide visual confirmation the gear is down and locked. Fully extended flaps have their own barber pole indicators.

The VS-1 BRI ejection seats are a controversial option: maintaining them can be costly, and some pilots are uncomfortable sitting on top of three explosive charges and a rocket motor designed to propel a pilot upward with a 16G acceleration. Ejection seat training must be completed using an FAA-approved syllabus, and recurrent training is mandated every two years. Ejection from ground level is prohibited below 81 KTAS since at low speeds the canopy may not completely disconnect from the aircraft. There is an electronic lock-out mechanism that will prevent both pilots from simultaneously ejecting into each other. In the case of a frozen canopy, there is a through-the-canopy ejection option, and in the case of an uncontrolled landing where the canopies become jammed there is an explosive canopy deployment module. Simplicity and economy are good arguments for having “cold” seats, but hot seats offer an extra added layer of safety; in the case of a low altitude emergency, there may not be time for a manual bail-out. Worldwide, there have been more than 7,560 documented fighter jet ejections with a pilot survival rate of 89 percent. One in three pilots sustained spinal compression injury. 

Drop down steps and spring-loaded panels provide ladder-like entry to the front and rear cockpits. After removing the six safety pins, the ejection seats are “armed” and ready to go. Maneuvering into the seats requires careful placement of feet through loops of white lanyard. These lines will tighten during ejection, pulling the pilot’s legs in for protection during egress. The integral seat belt/ejection harness is secured with a 4-point chest buckle. Twin ejection seat handles with integral triggers rise between the pilot’s thighs.

The start sequence begins by engaging the parking brake, which will not grab until hydraulic pressure builds during engine rotation. Master and engine control switches on the right bulkhead panel are toggled, and a minimum of 24 volts is confirmed. An APU port on the port side can be used if needed. When the annunciator panel “Do Not Start” and “Canopy Not Secure” lights are extinguished, the Saphir Starter button on the left side panel is depressed. A “Ready” light illuminates on the annunciator panel when the Saphir engine is up to speed and stabilized. This is the signal to engage the “Start Engine” button and position the throttle up to the idle/start position. An immediate whine fills the cockpit as the N1 RPM begins to climb. At 26 RPM, the engine lights and settles to an idle speed of about 56 percent. Electrical systems are engaged, the cabin pressurization lever on the right side is advanced, bleed air is switched on, and cabin temperature controls are set.

Taxiing the L-39 takes a bit of practice. The nose wheel casters passively and directional control is provided by differential braking. The brake lever is on the stick and look and feels like a bicycle hand brake or motorcycle clutch lever. Pulling the handle routes hydraulic pressure to the brakes, with differential braking provided by rudder pedal position. The desired rudder pedal is fully depressed to initiate a turn. This keeps your legs moving during taxi, especially with a crosswind. Before takeoff, the flaps are tested for full deflection using push buttons on the left side panel and then set to Take Off position. Speed brakes are cycled by activating a switch on the throttle handle. Engine run-up is to full MIL power, taking note of bleed air surge valve closings at 76 percent and 84 percent power, and measuring the speed of acceleration and deceleration of the engine. The AI-25TL engine is known for its slow spooling time: it takes anywhere from 8-11 seconds to go from idle to max power. This takes some getting used to, especially for pilots transitioning from piston or turboprop aircraft who are used to more ready power on demand. The relatively low bypass ratio of the turbofan contributes to power lag. A few L-39s sport the Garret TFE-731 motor. This conversion offers simpler operation, better fuel efficiency, much faster spooling times (less than three seconds) and obviates the need for the Saphir unit.

Take-off begins by advancing the throttle to the forward stop. Maximum N1 RPM should stabilize at just under 107 RPM. After checking temperatures and pressures, the brakes are released. Acceleration is brisk on the runway, and the 100-knot rotation speed comes up quickly with a ground roll of less than 1,500 feet. Positive rate, gear up, retract flaps at 140, and the plane settles in for a VY climb at 216 knots. Initial VSI at full MIL power is in excess of 4,000 fpm. Reduce power for normal climb to 101 percent and the VSI drops to 2,800 fpm. Sound levels are surprisingly low. A large turbocooler provides excellent cabin comfort even on hot summer days in Florida.  

Handling

Once airborne, the plane handles like a giant Bonanza. Controls are balanced and harmonious. A high-hat trim switch on top of the stick can be used to relieve pitch and roll stick forces. Speed builds quickly, especially in a dive, and the lack of a propeller coupled with the sleek planform means the plane doesn’t like to slow down. Approach Vmo (0.8 Mach) and the speed brakes will deploy automatically. 

Stalls are a non-item as the wing telegraphs critical angle of attack with a consistent shudder. Steep turns are easy once a proper sight picture is appreciated. Rudder input is minimal. Rolling maneuvers (barrel, aileron, hesitation) are smooth and gentle (remember the 20-second inverted time limit). Loops require almost 5,000 vertical feet. If done well enough to maintain at least 75 kts. at the top, the pilot will experience a sustained 4G pull. Under load, the staccato vibration of the G-suite pressurization system is heard and felt. Upright spins are limited to two turns, and tail slides are done with almost no risk of compressor stall. Pitch forces are light throughout the envelope, and the airplane responds to elevator input with great sensitivity. Roll response is a little slower, impeded by the mass of the tip tanks. Modifications are available to remove the tip tanks for increased speed and higher roll rates.

Since fuel and pressurization systems are automated, the pilot is free to just fly the plane. It’s a great cross-country machine with the caveat that endurance with reserves is under two hours. I flight plan for 500-mile legs when traveling cross-country. Much more than 90 minutes in the ejection seat becomes uncomfortable as seat cushions are not allowed. Specialty ejection seat pads can be found, but they are costly and don’t offer much relief.

Landing

Landing is commenced at a 1,500-2,000 ft AGL initial approach during which time speed should be bled down to about 200 kts. The downwind leg is flown just below the Vle speed of 180 kts. Gear down past the numbers, flaps approach on base, flaps landing on final (140-120 kts) and cross the fence at 100 kts. A Flettner tab on the left side of the elevator automatically extends with flap deployment to mitigate flap-induced pitching moments. Throughout the approach, engine RPM must be kept no lower than 80 percent in case of a balked landing. Spool-up time is long enough that a go-around may actually turn into a touch and go. Speed brakes are deployed as needed.

Touchdown is softened by robust trailing link gear. For short field work, the nose can be kept high for aerodynamic braking. Antilock brakes can be applied once the nose is planted to depress the nose-gear-mounted weight-on-wheels switch.  

Maintenance is made easier by large access panels and the simplicity of the systems. Dispatch reliability is excellent, and the plane offers few surprises.

With its good looks and warbird cachet, the L-39 turns heads on every ramp. Service and parts support for the airframe and engine are readily available domestically. There are several L-39s listed for sale, with prices ranging from $120,000 to $590,000 depending on aircraft age, engine time, avionics and modifications. There are a few specialty shops that are worth consulting if you are in the market. John Morgan at Pride Aircraft in Rockford, Illinois has been in restoration and sales since the first L-39s were imported to the U.S. He has an encyclopedic knowledge of the L-39 and his shop offers service, parts, and all popular airframe mods. North America’s only Ivchenko engine specialist is in Toledo, Ohio, at the eponymously-named AI-25TL company. Richard Hess and his team can rehab and repair the Ivchenko powerplant and are working on FAA overhaul approval. Nathan Jones, of Code 1 Aviation, has a robust brokerage and has been instrumental in developing the Garrett modification.

The L-39 Albatros offers speed, aerobatic capability and the thrill of flying a real fighter jet. It is arguably the ultimate PLJ. 

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